News:

Beta test the new forum at https://simutrans.forum/
Simutrans Sites
Know our official sites. Find tools and resources for Simutrans.

Observed oddity in log from obj_t, possibly related to desync?

Started by Matthew, May 08, 2022, 09:59:23 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Matthew

This is not a reproducible bug report, but an oddity that might lead to one.

I got desynced from B-B after a few hours' play. I noticed the following in the log file just before the desync:



Afterwards, I looked at (512,1650) and found this:



The bridge on the west side of (512,1650) is possibly on a bus route. I don't think there will have any other player activity around those tiles. The only other player activity I can think of above those tiles would be a plane?

The tiles ending in 695x do not exist - they are off the map.

So I looked at the tiles you find if you swap the X and Y co-ordinates from those log warning lines:



That sequence of tiles could only occur from an aircraft, I think.

These tiles are on the approach to a runway:



Maybe this is something to do with the desync, or maybe it was just some coincidental graphical glitch. But I thought I'd post it in case someone else can recognize it as important (or not).

This occurred on a self-compiled build.
(Signature being tested) If you enjoy playing Simutrans, then you might also enjoy watching Japan Railway Journal
Available in English and simplified Chinese
如果您喜欢玩Simutrans的话,那么说不定就想看《日本铁路之旅》(英语也有简体中文字幕)。

ceeac

This issue is also present in Standard: When running the big 12301 pak128 save from here with -debug 2, the log contains these lines:

Warning: karte_t::load():    loaded savegame from 0/2364, next month=1170210816, ticks=1169208280 (per month=1<<20)
Warning: convoi_t::go_alte_richtung():    convoy with wrong vehicle directions (id 15117) found => fixing!
ERROR: vehicle_base_t::leave_tile():    Fussgaenger 0x555b6ae790d8 could not be removed from (1680,2375,4)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com
ERROR: vehicle_base_t::leave_tile():    Fussgaenger 0x555b6ae793d8 could not be removed from (1680,2375,4)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com
Warning: obj_t::~obj_t():    Could not remove 0x555b59424508 from (261,830,0)
ERROR: vehicle_base_t::leave_tile():    Ding 0x555b7b4c4740 could not be removed from (2972,2474,7)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com
Warning: obj_t::~obj_t():    Could not remove 0x555b4dca1538 from (1679,2375,4)
ERROR: vehicle_base_t::leave_tile():    Fussgaenger 0x555b4dca1b38 could not be removed from (1679,2375,4)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com
ERROR: vehicle_base_t::leave_tile():    Fussgaenger 0x555b50bc1e98 could not be removed from (1679,2375,4)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com
Warning: obj_t::~obj_t():    Could not remove 0x555b72cde0c8 from (2417,1326,1)
Warning: obj_t::~obj_t():    Could not remove 0x555b72ce8668 from (178,2046,4)
Warning: obj_t::~obj_t():    Could not remove 0x555b50f6cff8 from (3091,10,1)
Warning: obj_t::~obj_t():    Could not remove 0x555b72ce7e28 from (2959,2494,4)
Warning: obj_t::~obj_t():    Could not remove 0x555b882d9868 from (1352,2889,0)
ERROR: vehicle_base_t::leave_tile():    Fussgaenger 0x555b87f73fb8 could not be removed from (2545,2253,8)
For help with this error or to file a bug report please see the Simutrans forum:
https://forum.simutrans.com

However, in my limited testing this only happened in single player.

jamespetts

Interesting - but difficult to decipher if it is in code common with Standard (and this code is not code that I have ever looked into). If this error occurs simultaneously on all clients and the server, it should not be responsible for a loss of synchronisation unless the fail state engages undefined behaviour or ends up engaging some code that is not network safe - but it is very difficult for me to evaluate that without knowing more about the object code in the first instance.
Download Simutrans-Extended.

Want to help with development? See here for things to do for coding, and here for information on how to make graphics/objects.

Follow Simutrans-Extended on Facebook.

ceeac

After some more investigation I managed to find and fix the issue for Standard: This was related to pedestrian generation, for example this scenario could happen:
  • There are 250 pedestrians on a single ground
  • The first vehicle of a convoi enters the ground
  • Up to 4 pedestrians are generated, causing the ground to be full
  • The second vehicle fails to enter the ground
  • When the convoi leaves the tile, the second vehicle fails be un-registered from the ground (because it was never registered in the first place)

So, to summarize, this is/was a bug, but not one that results in a desync. Check r10640/r10641.

jamespetts

Quote from: ceeac on May 20, 2022, 08:13:04 PMAfter some more investigation I managed to find and fix the issue for Standard: This was related to pedestrian generation, for example this scenario could happen:
  • There are 250 pedestrians on a single ground
  • The first vehicle of a convoi enters the ground
  • Up to 4 pedestrians are generated, causing the ground to be full
  • The second vehicle fails to enter the ground
  • When the convoi leaves the tile, the second vehicle fails be un-registered from the ground (because it was never registered in the first place)

So, to summarize, this is/was a bug, but not one that results in a desync. Check r10640/r10641.
Excellent, thank you for investigating this.
Download Simutrans-Extended.

Want to help with development? See here for things to do for coding, and here for information on how to make graphics/objects.

Follow Simutrans-Extended on Facebook.

prissi

It is even more likely that more pedestrians are walking on that tile. So one should also change 254 in pedestrians_t::hop_check also to 240.

Matthew

Quote from: ceeac on May 20, 2022, 08:13:04 PMSo, to summarize, this is/was a bug, but not one that results in a desync. Check r10640/r10641.

Thank you for investigating this issue and fixing it, ceeac. You have removed one bug and made it easier to diagnose other issues too.
(Signature being tested) If you enjoy playing Simutrans, then you might also enjoy watching Japan Railway Journal
Available in English and simplified Chinese
如果您喜欢玩Simutrans的话,那么说不定就想看《日本铁路之旅》(英语也有简体中文字幕)。